Publication DE102009051819A1 discloses an arrangement where a crane operator carries on his wrist an RFID card (transponder), and the control unit of the crane similarly has an RFID reader. In the technology of publication DE102009051819A1, the crane controllers, that is, the user interface, are only activated when the RFID card is within range of the RFID reader. This range is said to be 20-30 cm.
Publication DE102009051819A1, however, leaves some questions open. For example, need all holders of an RFID card have equal access rights? If all holders of an RFID card have equal access rights, what are these rights: are the rights set based on the most experienced or the least experienced operator? If, on the other hand, each holder of an RFID card has individual access rights, what are these rights and how are they set? Further, what exactly will happen in case the distance between the RFID card and RFID reader increases to more than the 20-30 cm referred to? If a crane operator, for example, places sunglasses on his eyes with two hands, should the crane be stopped by emergency stop or softly?
The question also remains unanswered of how the solution set forth in publication DE 102009051819 A1 and based on an RFID card and RFID reader is installed afterwards in an existing crane and/or its control equipment.